Centerless grinding machine



Filed Sept. 14. 1928 2 Sheets-Sheet 1 /N VE/V TUE: 64 I JMYES/IW/LL/A M5, F g" 5 15 1 g6 @424 F %am CENTERLESS GRINDING MACHINE Filed Sept. 14, 1928 2 Sheets-Shem 2 a the wheels.

Patented Oct. 11, 1932 UNITED STATES PATENT ,OFFICE JAMES F. WILLIAMS, LYNDHURST, NEW JERSEY, ASSIGNOR TO GENERAL MOTORS CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE CENTERLESS GRINDING MACHINE Application filed September 14, 1928. Serial No. 805,915.

. guiding work pieces in such a way that the points of contact of the work with the tilted wheel are maintained at the same distance from the line of wheel centers for work of dillerent diameters. Another object is to 1 provide improved work guides for centerless grinders so that dressing of the tilted wheel is simplified.

To these ends and to improve generally and in detail upon machines of this character, the invention also consists in the "31'1- ous matters hereinafter disclosed and claimed. In its broader aspects, the invention is not necessarily limited to the specific mechanism selected for illustrative purposes in the accompanying drawings in which Fig. 1 is a side elevation, the middle portions of the work guides being broken away.

Fig. 2 is a side view, to a larger scale, of one end portion of the work guides.

Fig. 3 is an end view of the work guides.

Fig. 4 is a perspective view of one of the levers.

Fig. 5 is a perspective view of a bushing.

Fig. 6 is a rear view of one of the brackets with some of the guide structure.

Fig. 7 is a side elevation of theguide structure arranged to guide the work below the wheel centers.

Fig. 8 is a similar view with the guides in another position for smaller work.

Figs. 9, 10 and 11 are diagrams.

Referrin to diagrammatic Figure 9, a round wor -piece W is indicated at the throat of a centerless grinding machine having a grinding wheel G and a regulating wheel R, tangents U and L representing the positions of upper and lower work guides.

The work-piece is shown contacting with the wheels at a and b in the line of centers of In such a structure, it is obvious that the upper work guide U and the lower work guide L should be raised and lowered in equal degree to fit work of a larger size, if the points of contact a and b are kept at the grinding throat in the line of wheel centers. When these conditions are maintained it is a simple matter to dress the regulating wheel R, as by a diamond (1 arranged diametrically opposite the point b. However, there are reasons why it is desirable to grind the work below center as indicated in Fig. 10. One reason is that the usual tendency to produce work having three high spots is diminished because the points of contact a and 5 do not then come on diametrically opposite points of the work W.

As is well known, the regulating wheel of a centerless grinder is usually tilted to feed the work through the grinding throat and this necessitates a slight concavity in the wheel of hyperboloidal form to present a straight line of contact to cylindrical work. If the work is ground below the line of wheel centers as in Fig. 10, and if the centers of all sizes of work-pieces are kept at the same point a, then the upper and lower work guides U and L can be simply spread apart more or less in equal degree as before to fit the larger or smaller work. In this case, however, the distance of the point of contact a or b from the line of wheel centers, for smaller work pieces W, is greater than the distance of the point of contact a or b for larger work pieces W. This variation in the points of contact is what greatly complicates wheel dressing and requires elaborate dressing mechanism and calculation to determine the concave surface to generate on the tilted regulating wheel.

According to this invention, as diagrammatically illustrated in Fig. 11, upper and lower guides U and L are so constructed as to maintain the point of contact I), for all sizes of work, at a constant distance from the line of wheel centers. This simplifies wheel dressing because a diamond d can be mounted on a level with the point 6 to travel parallel to an element of the cylindrical work at point 6. The mounting for the work uides however must take care of the con ition illustrated wherein tangents U, U U represent upper work guides and tan ents L, L L represent lower work guides or three difierent sizes of work W, W W which all have line contact with the regulating wheel R at b. To

maintain the contact point I), as the work increases in diameter, it Will be noted that the work centers 0, 0 and 0 must be located lower and lower on radial line 1"-b and this descent of centers requires that the lower work guides be lowered more than the upper work guides be raised. The guides are accordingly carried on a lever or linkage system in which the lower arms are capable of being made longer than the upper ones by an amount depending on the location selected for the point I).

The work guides comprise upper and lower continuous T-irons 8, each having a vertical web 10 entering a notch 12 in a V-bar 14 to which guide plates 16 are removably attached. At the work receiving end, the plates 16 are extended beyond the bars 14 and connected by a short V-block 17. One end of each bar 14 carries a pair of short blocks 20 embracing the vertical web 10 and secured to it by rivets 22. The blocks have bevelled ends 24 flush with the V-bars 14 and also supporting the guide plates 16. Each T-iron also carries a pair of similar blocks 26 a little way from the end between sections of the V- bar 14. The blocks 20 and 26 and the vertical webs 10 have reamed openings 28 traversed by pivot studs 30 and 32 which pivotally suspend the work guides on levers which keep them parallel. The studs extend through openings in sleeves 34 and 36, respectively, on a pair of constantly parallel levers having offset arms 38 and 40 connected to a central boss 42 having a bore 43. Each lever has its opening 43 sleeved over and fixed on a round end section 44 of a stud having opposite openings 46 for a set screw 48 by which the stud is rigidly secured to the lever in either one of two positions. The stud has a squared end 50 and a round pivot section 52 with respect to which the end section 44 is eccentric. The round section 52 forms an adjustable pivot for the lever and is rotatably mounted in a round opening 54 of a bushing 56 having a head with flattened sides 58 by which the bushing can be turned. The bushing has opposite openings 60 and its opening 54 is eccentric with respect to its outer periphery, the amount of eccentricity being the same as that of the pivot stud. The bushing enters a round opening 62 of a bracket 64 and is held in either one of two positions by a set screw 66 placed in a tapped opening of a boss 68 on the bracket 64.

The bracket 64 comprises a pair of uprights connected by a base plate 69 and one upright has arcuate slots 70 to receive the studs 30 and 32 which are clamped in adjusted position by nuts engaging washers 72. The base plate is attached to a bracket 74 by bolts, a removable spacer 76 being interposed between. The uprights of the bracket 64 are connected at the top by a tie plate 78. Both ends of the apparatus are similar but one of the uprights of one bracket 64 is provided with screw adjusting mechanism. This bracket has an upper boss 80 and alower boss 82, each having a tapped opening fora screw 84 which engages the adjacent lever, nuts 86 holding the screws in adjusted position.

In the position illustrated in Fig. 1, the machine is arranged to grind work on a level with the wheel centers. The hole 43 of each lever is located nearer one end than the other by an amount which can be compensated for by the eccentricity of the pivot stud 52 with respect to its end section 44 which can be secured to the lever in either of two positions by the set screw 48. In Fig. 1, the arrangement is such that the pivot 52 is half way between the end pivots 30 and 32 thereby satisfying the requirements for grinding on a level with wheel centers wherein the upper and lower guide bars should move equally to fit work of different sizes.

In Fi g. 7, the machine is arranged to grind the work below the wheel centers. The spacers 76 are removed from below the brackets 64 to lower the guides bodily. Then the eccentric pivot stud 52 is arranged above the hole 43 of the lever and in a diametrically opposite position with respect to the former setting so that the pivot 52 is raised and nearer to the pivot 30 than to the pivot 32 thereby making the lower arms 38, in efiect, longer than the upper arms 40. Also the hole 54 in the eccentric bushing 56 is in a diametrically opposite position with respect to its formerposition in order to form a bearing for the pivot 52 in its raised position while still allowing the pivots 30 and 32 to move in the arcuate slots 70 when the lever is swung to adjust the upper and lower work guides to the work. The pivots 30 and 32 have sufficient lost motion with the sides of the slots to allow for the differences in the radii of the arcs of movement when the pivot center 52 is arranged in the two different positions. The relative lengths of the shorter upper arm and the longer lower arm are indicated by the dimensions D and E and the ratio depends on the distances of the point of contact I) (of the work with the wheel) from the upper and lower tangents U and L. In other words the pivot 52 is located on a level with the point of contact 5 While the pivots 30 and 32 are adjusted simultaneously to keep the upper and lower guides on a level with the tangents U and L. The guides always remain in parallelism and so do the levers and adjustment of one pair of levers compels the other to take a similar position. In Fig. 8, the guides are arranged for smaller work (effected by swinging the levers) but the distance of the point of contact b from the line of wheel centers remains constant.

The machine can also be arranged to grind with the point of grinding contact at a con- Lid stant distance above the wheel centers by reversing the levers but the below center arrangement is preferred because the wheels tend to hold the work down. Several sets of wheels may be arranged along the sides of the work guides for successively treating the work. It is the regulating wheel of centerless grinders which is usually tilted and so presents the problem of properly dressing its concave face but the invention is also applicable to dress a tilted grinding wheel. The diamond Z can be mounted in any suitable way to traverse the tilted wheel but should be located on a level with the point of grinding contact and move parallel to an element of the cylindrical work. When the invention is; applied to centerless grindng machines wherein one wheel is higher than the other, the work, of course, will then contact with the tilted wheel at one side of the line of wheel centers while the opposed bars open laterally.

I claim:

1. In a machine of the character described, a grinding wheel and a regulating wheel, one of said wheels being tilted to feed the work, a work guide for conducting work-pieces between the whcels with the point of work and wheel contact at a definite distance away from the line of wheel centers, and a dressing tool located at a point remote from the work path and at the same distance from the line of wheel centers for dressing the tilted wheel; substantially as described.

2. In a grinding machine having opposed wheels providing a grinding throat between them, a Work supporting bar extending between the wheels, arms pivoted to the bar and having pivotal supports out of the line of wheel centers and at the same distance from the line of wheel centers as with the point of work and wheel contact; substantially as described.

3. In a grinding machine having opposed wheels providing a grinding throat between them, one of the wheels being tilted to feed the work, a work supporting bar extending between the wheels, arms pivoted to the bar and having pivotal supports out of the line of Wheel centers and at the same distance from the line of wheel centers as the point of work and wheel contact, and a dressing tool at the same distance from the line of wheel centers and located on the opposite side of the tilted wheel from its point of work contact; substantially as described.

4. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them parallel, and means for angularly adjusting the levers for varying the distance between the bars; substantially as described.

5. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them paralle pivot studs for allowing angular adjustment of the levers, and means for varying the distance of the pivot studs from the ends of the levers; substantially as described.

6. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them parallel, pivot studs for allowing angular adjustment of the levers, means for varying the distance of the pivot studs from the ends of the levers, means for supporting the pivot studs, and means for angularly adjusting the levers; substantially as described.

7. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposed sides of the work, levers connecting said bars for holding them parallel, pivot studs for allowing angular adjustment of the levers, means for varying the distance of the pivot studs from the ends of the levers, brackets for supporting the pivot studs, screws for angularly adjusting the levers, and means for clamping the levers to the brackets in adjusted position; substantially as described.

8. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work bars, levers connecting said bars for holding them parallel, pivot studs projecting from the levers for allowing angular movement of the levers, and eccentric mountings for securing the studs to the levers to position the studs midway of the ends of the levers or at different distances therefrom; substantially as described.

9. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work bars, levers connecting said bars for holding them parallel, pivot studs projecting from the levers for allowing angular movement of the levers, eccentric mountings for securing the studs to the levers to vary the distance of the studs from the ends of the levers, and eccentric bushings receiving the studs; substantially as described.

10. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work bars, levers connecting said bars for holding them parallel, the levers having openings oiiset from their centers, eccentric members in the openings and having projecting pivot studs, and means for fixing the eccentric members in a plurality of positions in the lever openings to locate the studs midway of the ends of the lovers or at different distances therefrom; substantially as described.

11. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging oppositc sides of the Work and having pivot studs, levers supporting the studs, brackets pivotally supporting the levers and having arcuate slots receiving thestuds, and means for clamping the studs in the slots; substantially as described.

12. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them parallel, the lovers having adjustable pivot studs, brackets having openings, eccentric bushings in the openings and receiving the pivot studs, and means for securing the bushings in their openings in a plurality of positions; substantially as described.

13. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars, pivot studs for the levers, means for locating the pivot studs midway of the ends of the levers on the line of wheel centers, and means for locating the pivot studs at different distances from the ends of the levers and out of the line of wheel centers; substantially as described.

14. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them par allel, pivot studs for allowing angular adjustment of the levers, and means for supporting the studs on a line with wheel centers for on-center grinding or on a line with the point of work and wheel contact for oil'- center grinding; substantially as described.

15. In a grinding machine having opposed wheels providing a grinding throat between them, a work guide comprising opposed bars engaging opposite sides of the work, levers connecting said bars for holding them parallel, pivot studs for allowing angular adjustment of the levers, means for supporting the studs on a line with wheel centers for oncenter grinding or on a line with the point of work and wheel contact for off-center grinding, and means for varying the distance of the pivot studs from the ends of the levers; substantially as described.

16. In a grinding machine having opposed wheels providing a grinding throat between them, a work support extending between the wheels, means for locating the support in a fixed position such that a round work-piece will have contact With the wheels at a definite and predetermined distance away from the line of Wheel centers, and means for adjusting the work support in a manner so related to the diameter of the work as to insure that work of different selected diameters will be supported in a position to make contact with the wheels at the same distance from the line of wheel centers; substantially as described.

17. In a machine of the character described, a grinding wheel and a regulating wheel spaced apart to form a grindin throat between them, a work support extending between the wheels, the axis of one of said wheels and the work support having a relative inclination to produce a tendency to feed a work-piece endwise along the support, and said wheel being contoured to have line contact with the work-piece at a predetermined distance away from the line of Wheel centers, and means for moving the work support to selected positions in a predetermined relation to the size of the work to maintain said line of contact at said predetermined distance from the line of wheel centers with the wheel remaining of the same contour for all sizes of work; substantially as described.

In testimony whereof I hereunto afiix my signature.

JAMES F. WILLIAMS.

CERTIFICATE OF CORRECTION. 5

mm: No. 1, 882, 465. 4 October 11, 1932.

JAMES F. WILLIAMS.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page .3, line 41, claim 2, strike out the word "with"; line 88, claim 7, for "opposed" read "opposite";'

lines 101, 113 and l25 claims 8, 9 and 10, respectively, strike out the word 7 "bars"; and that .the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. 1 a 1 Signed and sealed this 20th day oi December A. D. 1932.

' M. J. Moore, (Seal) I, Acting Commissioner of Patents. 

